Animals with more sophisticated nervous systems than nematodes can survive vitrification.

http://www.ncbi.nlm.nih.gov/pubmed/20086136

Even more sophisticated neural networks, mammalian brain slices, can now be vitrified with present technology.

http://www.21cm.com/pdfs/hippo_published.pdf

Of course it is what happens to whole brains that are vitrified that really matters to cryonics. The only paper published so far on the technology presently used in cryonics applied to whole brains is this one

http://www.alcor.org/Library/pdfs/Lemler-Annals.pdf

with more micrographs from that study here

http://www.alcor.org/Library/html/cambridge.html

and many more here

http://www.alcor.org/Library/html/micrographs.html

Unlike slices, there is no expectation that cell viability is preserved in whole brains because the cryoprotectant exposure time is longer. However connectivity and extensive biochemical information is believed to be preserved, as these micrographs suggest. It is presumed, but not proven, that the effect of thermal stress fractures at cryogenic temperatures is displacement of fracture planes. This would theoretically still preserve connectivity information, although requiring hyper-advanced technology to do anything with that information.

First off, for it to preserve no information at all would be extremely surprising. If there are physical structures, that's some kind of information. But that's not the question we're interested in -- we are interested in relevant information. As you say, preserving a neural network is the "holy grail" (at least if you aren't counting loftier yet less crucial goals like reversible whole-body suspension). Notwithstanding, we do have evidence that there is at least some brain structure being preserved -- there are pictures and everything.